orthogonal

There are an infinite number of normalized vectors orthogonal
to the instance. This method picks up one of them almost
arbitrarily. It is useful when one needs to compute a reference
frame with one of the axes in a predefined direction. The
following example shows how to build a frame having the k axis
aligned with the known vector u :

angle

This method computes the angular separation between two
vectors using the dot product for well separated vectors and the
cross product for almost aligned vectors. This allows to have a
good accuracy in all cases, even for vectors very close to each
other.